Right-click microemulator.jar and select Properties, Permissions and tick Allow executing file as program. Click Open button to launch the application. Next, you will get a warning that this application is from an unidentified developer. Right-click microemulator.jar and choose Open from the context menu. Once it’s downloaded, unzip it and move the resulting folder to a convenient location, Program Files on Windows or Applications on Mac, for example. Go to the MicroEmulator download page and click on microemulator-2.0.4.zip to start the download. If you’re running Ubuntu, you can install the OpenJDK Java 7 Runtime from the Ubuntu Apps Directory. Just proceed with the download, and once this is finished, open the Java installer and follow the steps to complete the installation. On the next screen, you may get a warning that Java might not run inside your browser: this is not important as we will run Java on the system level. If you’re using Windows or Mac, go to the Java download page and click on the “Free Java Download” button.

To make this as straightforward as possible, we’ve outlined all the necessary steps below. In a nutshell, you’ll need Java and MicroEmulator, in which you’ll run an instance of Opera Mini for J2ME-enabled feature phones.

However, as Opera Mini is a proxy browser with limited JavaScript functionality, it’s important you test your site in it. Opera Mini is used by more than 244 million people per month, and for many of them, it’s the only way they can access the internet. For development and testing purposes, it can be useful to install Opera Mini on your computer.

Java emulator mac